Plasma arc torches are used in the cutting and marking of metallic materials. A plasma arc torch generally includes a torch body, an electrode mounted within the body, a nozzle with a central exit orifice, electrical connections, passages for cooling and arc control fluids, a swirl ring to control the fluid flow patterns, and a power supply. Gases used in the torch can be non-reactive (e.g., argon or nitrogen), or reactive (e.g., oxygen or air). The torch produces a plasma arc, which is a constricted ionized jet of a plasma gas with high temperature and high momentum.
Due to their versatility, plasma torches are finding uses in an increasing number of applications. Hand-held torches are now being used in ever more intricate situations, including those where access to portions of the workpiece can be difficult. Automated (mechanized) torches are being used to cut special shapes, including cuts having bevel surfaces. One way to make such cuts is to angle the torch head, such that the plasma arc emitted from the torch is not perpendicular with a planar workpiece that is being cut. Expensive and extensive automated systems have been devised to automatically rotate torches to perform bevel cuts.
Technical hurdles related to the articulated joint have thus far prevented such concepts from reaching the market. One issue preventing certain manufacturers from entering the articulated torch market has been the extensive use of torch designs with moving plungers inside the torch head. These “blowback” designs utilize flexible wires inside the torch handle, which constrain the torch design and make an articulated torch very difficult to implement into the design. See, e.g., U.S. Pat. No. 4,902,871 issued to Sanders et al. entitled “Apparatus and Process for Cooling a Plasma Arc Electrode”. As mentioned above, performing a bevel cut using a mechanized plasma arc torch results in an expensive design requiring large motors to move the torch. The motors used to position the torch during the cut impose a mechanical stress on the leads of the torch, resulting in premature failure of the leads.